The practice of freeze branding livestock is well defined and understood. Essentially the pigment cells of hair follicles are killed by the cold temperatures incurred during freeze branding. Once the pigment cells are dead, any subsequent hair grown at the freeze-branding site lacks pigment and is therefore white. In this manner, livestock can be permanently marked for individual identification.
During the freeze branding process, application of too low a temperature will kill the hair follicles, and no hair will grow at the branding site. Insufficiently low temperatures at the site will not kill the pigment producing cells entirely or at all, which results in a mixture of white and indigenously colored hair, or no mark at all.
Freeze branding is generally accomplished by using a solution of dry ice and alcohol or a liquid nitrogen bath to cool bronze or copper branding irons. The irons are submerged in the bath until they reach the desired temperature. The brands are then applied to a shaved section of hide meant to be branded. Typical application times are from 20 seconds to one minute. In practice, it is often difficult to assure that the branding irons are cooled to a consistent temperature. Additionally, ambient conditions can have a significant effect on the temperature of the branding irons during the branding process.
It has become a common practice for stock owners to apply individual, multiple digit freeze brands to their livestock. The purpose of this practice is to permanently and uniquely mark livestock for individual identification. It is now apparent that this practice will likely become more popular in light of recent developments relating to BSE (mad cow disease) in the U.S. and the likelihood of a national bovine identification system, as well as the likely implementation of Country of origin labeling (COOL) by the United States Department of Agriculture.
Utilizing known methods, however, it is difficult to apply individual multiple-digit freeze brands to more than 10 head per hour. Accordingly, there is a need for a more expeditious method of applying individual, multiple-digit freeze brands.
U.S. Pat. No. 3,485,060 to Ziegler discloses a livestock branding apparatus constructed such that various branding letters and symbols are interchangeable. The brand symbols, which are made up of a series of finger-like elements having ducts that provide vents for expanding gases caused by evaporating refrigerant, are mounted on individual box structures. The fingers extend a substantial distance into the interior of the box, which defines a plenum chamber for receiving a liquid refrigerant, to provide maximum surface contact with the liquid refrigerant. The fingers are supposedly cooled to a branding temperature by the refrigerant evaporation. Heat conduction through the finger elements is supposed to keep them at a temperature very near that of the vaporizable liquid refrigerant.
A significant drawback to the Ziegler's apparatus is the likely difficulty of changing letters and symbols with its unwieldy refrigerant fluid structure. Ziegler's supposedly interchangeable brand symbols. The refrigerant evaporation that is supposed to cool the fingers to a branding temperature cannot help but also cool the box, which is too small and thin-walled to have much insulation from the surrounding air. Humidity in the surrounding air thus can be expected to form ice on the box during the branding process. With the ice and the extremely cold temperature that the box can be expected to reach, it does not appear at all convenient to detach the box from the sizable surface of contact it makes with Ziegler's tubular support member 24 and manifold 22.
Another significant drawback of Ziegler's apparatus is that the refrigerant spray emitting from the branding fingers' vents can be expected to form a vapor barrier that interferes with thermal conduction between the fingers and the branding subject. In addition, the branding fingers present only a small surface area of contact with the branding subject, an area that is maximized by painfully driving the fingers into the subject's hide. In addition, it is doubtful that the fingers would have enough thermal inertia to remain sufficiently cool to effect a proper freeze brand.
U.S. Pat. No. 3,358,648 to Berens discloses a freeze branding apparatus in which heat-conductive tubing is bent or otherwise fashioned into the shape of brand insignia that are to be applied. The tubing is connected to a supply of “liquified gas” through flexible heat-insulated tubing and is cooled by passing a cryogenic fluid, i.e., the “liquified gas,” through it. The device can include a plurality of differently shaped tubings having portions formed to the shape of different insignia, which can be interchangeably coupled to the flexible tubing with a quick disconnect coupling.
Clearly, however, Berens' apparatus is unsuitable for the simultaneous application of multiple insignia. Using the apparatus to apply multiple-digit freeze brands would require multiple separate applications, which would entail either the labor-intensive task of replacing insignia for each digit or the expense of keeping multiple branding apparatuses on hand for the digits being used. In addition, a great deal of difficulty can be expected in making multiple separate applications of an orderly sequence of branding digits to a branding subject that is living, moving, and (especially after the first application) very possibly resistive to the procedure.
Accordingly, the need remains for a way of effectively applying simultaneous branding digits to a subject while permitting convenient changing of the digits to be applied.